Many computing environments process and transmit information having different security classification levels. For example, military computing environments process classified information having security levels such as top secret and secret, as well as unclassified information. Typically, unclassified information is separated from classified information in these computing environments, so that classified information is not improperly passed to an unsecured computing environment. This separation is often accomplished through hardware and/or software that creates partitions within the environment where the information is stored, effectively creating an electronic barrier between the various levels of sensitive information. For example, partitioned processing environments have been developed that enable single processors to host Multiple Independent Levels of Security (MILS). One example of such a processor is the AAMP7G processor manufactured by Rockwell Collins of Cedar Rapids, Iowa, which utilizes a National Security Agency (NSA) certified brickwall Partition Management Unit (PMU) to enforce separation of processes.
In some operating systems, it is not possible for such a processor to operate directly from flash memory and/or from other nonvolatile storage elements, for example, devices including nonvolatile memory, such as re-writable, general purpose mass storage devices. Due to the need to trust and ensure the authenticity of the code being executed, such systems would require a processor connected to a very large RAM component capable of storing executable code loaded from the nonvolatile storage element. Due to Application Specific Integrated Circuit (ASIC) die limitations, growing software executable sizes, and the need for MILS in some applications, there is a need to limit the size of the on-die RAM while still maintaining the integrity of the executable code and allowing a processor to execute code loaded from a nonvolatile storage element.